I think it's illegal to be honest. We usually get UK-ised versions of US TV shows (especially car chases and police action ones) but we've never had a UK Dog the Bounty Hunter (even though we do get that quite often over here). I assume it's either illegal or nobody is interested. To be honest if bounty hunting wasn't illegal, painting your car in the police colours would be, It's impersonating a Police Officer (which you can be jailed for..)